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Pharm Test 3 > Protein Synthesis Inhibitors II- Tetracyclines, Sulfonamides, Chloramphenicol, UTI agents > Flashcards

Protein Synthesis Inhibitors II- Tetracyclines, Sulfonamides, Chloramphenicol, UTI agents Flashcards

1
Q

Tetracyclines

A

First Generation: TETRACYCLINE

Second Generation: DOXYCYCLINE, MINOCYCLINE

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2
Q

Glycylcyclines

A

Minocycline derivatives

Ex. Tigecycline

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3
Q

Tetracyclines/Glycylcyclines Mech of Action

A

REVERSIBLY binds the 30S ribosomal subunit

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4
Q

Tetracyclines/Glycylcyclines- Bactericidal or Bacteriostatic?

A

Baceteriostatic; bactericidal when present at high concentrations against very susceptible organisms

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5
Q

Mechanisms of Resistance against Tetracyclines/Glycylcyclines Abx

A

Acquisition of genes on mobile elements:

  • EFFLUX PUMPS
  • RIBOSOMAL PROTECTION PROTEINS
  • ENZYMATIC INACTIVATION

Cross-resistance observed between tetracyclines, except for Minocycline
Tigecycline resistant to these mechanisms

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6
Q

Tetracyclines Spectrum of Activity

A

Gram (+) Aerobes:
Staph aureus (primarily MSSA)
others

Gram (-) Aerobes
Anaerobes

Misc.:
LEGIONELLA
CHLAMYDOPHILA
CHLAMYDIA
MYCOPLASMA
UREAPLASMA
RICKETTSIA
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7
Q

Tigecycline Spectrum of Activity

A

Broader spectrum of activity than tetracyclines
Gram (-) Aerobes:
NOT PROTEUS SPP. OR PSEUDOMONAS AERUGINOSA!!

Anaerobes:
BACTEROIDES SPP.

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8
Q

Tetracyclines/Glycylcyclines Absorption

A

Absorption impaired by di- and tri-valent cations (ex. dairy, vitamins)

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9
Q

Tetracyclines/Glycylcyclines Distribution

A

widely distributed
PROSTATE
minimal CSF penetration

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10
Q

Tetracyclines/Glycylcyclines Elimination

A

Kidney- DEMECLOCYCLINE/TETRACYCLINE
Non-renal routes- DOXYCYCLINE, MINOCYCLINE (metab), TIGECYCLINE (biliary)

TETRACYCLINES/TIGECYCLINE ARE MINIMALLY REMOVED DURING HEMODIALYSIS

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11
Q

Tetracyclines/Glycylcyclines Clinical Uses

A 
ROCKY MOUNTAIN SPOTTED FEVER
Respiratory infections
STDs
Treatment/prophylaxis of malaria
Polymicrobial infections (Tigecycline)
Acne
SIADH (demeclocycline)
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12
Q

Tetracyclines/Glycylcyclines Adverse Effects

A

PHOTOSENSITIVITY
G.I.- NAUSEA, VOMITING
RENAL- FANCONI-LIKE SYNDROME W/ OUTDATED TETRACYCLINE
PREGNANCY CATEGORY D
Hypersensitivity, particularly of the skin

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13
Q

Sulfonamides

A

1st effective abx used to prevent/treat infections

Led to a dramatic reduction in morbidity/mortality w/ treatable infections

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14
Q

Sulfonamides Mech of Action

A

INHIBITS DIHYDROPTEROATE SYNTHETASE

- inhibits incorporation of PABA into tetrahydropteroic acid

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15
Q

Sulfonamides- Bactericidal or Bacteriostatic?

A

Bacteriostatic

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16
Q

Trimethoprim

A

Developed in the 1950s

17
Q

Trimethoprim Mech of Action

A

INHIBITS DIHYDROFOLATE REDUCTASE

- interferes w/ conversion of dihydrofolate to tetrahydrofolate

18
Q

Trimethoprim-Sulfamethoxazole (TMP-SMX, Bactrim) - Bactericidal or Bacteriostatic?

A

BACTERICIDAL in combo w/ synergistic activity

19
Q

Where Timethoprim-Sulfamethoxazole Act

A

PABA–>DIHYDRO. ACID–>TETRA. ACID–>PURINES

PABA–(Sulfamethoxazole)–X DIHYDROFOLIC ACID

DIHYDROFOLIC ACID–(Trimethoprim)–X TETRAHYDROFOLIC ACID

20
Q

Mechanisms of Resistance Against TMP-SMX

A

Sulfonamides

  • resistance widespread
  • PABA overproduction
  • Structural Change of Dihydropteroate synthetase
  • plasmid mediated production of drug resistand DHPS or decreased bacterial cell wall permeability to sulfonamides

Timethoprim

  • chromosomal or plasmid mediated
  • plasmid-mediated production of dihydrofolate reductase resistant to trimethoprim
  • changes in cell permeability
21
Q

TMP-SMX Spectrum of Activity

A

Gram (+): STAPH AUREUS, (incl. some MRSA)
Gram (-): STENOTROPHOMONAS MALTOPHILIA
Other: PNEUMOCYSTIS CARINII
Anaerobes: no activity

22
Q

TMP-SMX Absorption

A

available IV and PO

rapidly and completely absorbed

23
Q

TMP-SMX Distribution

A

Good distribution, esp. PROSTATE
Penetrates the CSF (TMP more than SMX)
SMX is 70% protein bound

24
Q

TMP-SMX Elimination

A

Both are eliminated by kidney

DOSE ADJUSTMENTS REQUIRED IN PATIENTS W/ CRCL<30ML/MIN

25
Q

TMP-SMX Clinical Uses

A 
ACUTE, CHRONIC, OR RECURRENT UTIs
ACUTE OR CHRONIC BACTERIAL PROSTATITIS
SKIN INFECTIONS DUE TO CA-MRSA
Bacterial Sinusitis
Nocardia
Pneumocystis carinii pneumonia
Stenotrophomonas
Toxoplasmosis
Listeria monocytogenes
26
Q

TMP-SMX Adverse Effects

A 
Hematologic: LEUKOPENIA, THROMBOCYTOPENIA, anemias, eosinophilia, agranulocytosis
HYPERSENSITIVITY- RASH, Stevens-Johnson, others
CRYSTALLURIA
G.I.
CNS
Renal Toxicity
Drug-induced Lupus
Serum sickness-like syndrome
27
Q

TMP-SMX Drug Interaction

A

Phenytoin- increases phenytoin levels
Warfarin- increases anticoagulant effect
Methotrexate- decreases renal clearance

28
Q

TMP-SMX Dosing

A 
- comes in single and double strength
DOUBLE STRENGTH (DS)= 160MG TMP AND 800MG SMX
29
Q

Chloramphenicol

A

Introduced in U.S. in 1949
No longer used here b/c of adverse effects
Still used in developing world

30
Q

Chloramphenicol Mech of Action

A

Binds to 50S subunit of 70S ribosome

Prevents peptide bond formation

31
Q

Chloramphenicol- Bactericidal or Bacteriostatic?

A

Bacteriostatic except for:
H. influenza
Strep. pneumo
N. meningitidis

32
Q

Mechanisms of Resistance to Chloramphenicol

A

Reduced permeability or uptake
Ribosomal mutation
Acetyltransferase inactivation

33
Q

Chloramphenicol Pharmacology

A

Absorption- well absorbed
Distribution- lipid soluble, not highly protein bound, CSF levels 30-50% of serum levels
Elimination- metabolized by liver, excreted by kidneys

34
Q

Chloramphenicol Spectrum of Activity

A

Gram (+)- unreliable against Staph aureus, not active against enterococci
Gram (-)- not active against P. aeruginosa
Anaerobes- Gram (-) and (+)

Rickettsiae sp.
spirochetes
Chlamydia
Mycoplasma

35
Q

Chloramphenicol Clinical Uses

A

None in U.S.
Developing World- pneumonia, bacterial meningitis, typhoid fever
Rocky Mountain Spotted Fever

36
Q

Chloramphenicol Adverse Effects

A 
Hematologic
Gray baby syndrome
Optic neuritis
anaphylaxis
GI intolerance
stomatitis
porphyria
37
Q

Urinary Tract Agents

A

Nitrofurantoin

Methenamine

38
Q

Urinary Tract Agents Mech of Action

A

Nitrofurantoin- poorly understood, binds to ribosomal proteins, inhibits stuff
Methenamine- Converted in acid pH to ammonia and FORMALDEHYDE, Formaldehyde denatures proteins & nucleic acids

39
Q

Mechanisms of Resistance against Urinary Tract Agents

A

Nitrofurantoin- poorly understood, rare, chromosomal or plasmid-mediated
Methenamine- alkaline urine, no resistance to formaldehyde described

Pharm Test 3 (10 decks)

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